This invention relates to a filling system for adding replenishment liquid to multiple containers such as battery cells.
Secondary battery cells normally require replenishment water to make up for water lost from the electrolyte due to evaporation and electrolysis. The process of adding water is simple when the number of battery cells is small and the batteries are readily accessible, such as automobile batteries, where battery cells can be inspected and filled manually.
With larger batteries, such as batteries for producing tractive forces and standby power supplies, the number of battery cells is often so large and accessibility so poor, that the task of replenishing by hand can become particularly difficult and time consuming.
A variety of filling systems have been developed which provide requisite water to all the battery cells via a suitable supply line. Conventional systems for providing replenishment water to filler units disposed on the battery include gravity tanks, utility water mains, pressure tanks and pumping arrangements which feed the replenishment water through a conduit arrangement to all the filler units on the battery. Some systems apply replenishment water at an inlet port, and draw out gas and water from an outlet port of the conduit arrangement, and require the entire filling system interior to be sealed off from the surroundings.
There have been designs which utilize the supply pressure of the replenishment water to assist an internal mechanism to turn off the flow of water as the electrolyte reaches the desired level. In another type of design, a pressure sensing tube arrangement detects the rising electrolyte, and a consequent rise in pressure inside the tube arrangement causes a float to rise and close a valve, thereby shutting off the flow of replenishment water into the respective cells.
The control mechanisms of the various types of filler units are comparatively complex and therefore costly to manufacture. An advantage of the pressure sensing tube arrangement is its comparatively low cost compared to some other designs, but the requisite mechanism for establishing a substantially constant head of liquid in an upper vessel of each filling device may add unnecessary extra cost to the manufacturing process. Furthermore, the installation work required to fit the requisite filler units to a battery entails the plugging in, and individual connecting up of all the individual filler units in a comparatively time consuming operation.
Some of these disadvantages can be overcome by the use of a unitary filler unit similar to that disclosed in U.S. Pat. No. 4,544,004 which provides multiple outlet porting to feed replenishment water simultaneously into all the cells of a multi-celled battery. This example, while possessing some advantage of constructional simplicity over a multiplicity of filler units, does present significant difficulty at installation since it cannot be readily fitted into the screw in type vent apertures of conventional batteries.
A plug-in arrangement which allows a tray-like multiple vent cap to be fitted into an array of threaded vent apertures on a battery is described in U.S. Pat. No. 5,356,734. Whilst facilitating attachment, these vent caps are readily dislodged in use due to fatiguing of the plastic material of which they are made.
Screw-in arrangements which allow individual ganged vent caps to be fitted into an array of threaded vent apertures are described in U.S. Pat. Nos. 4,477,542 and 5,525,438. Whilst possessing the advantage of remaining in place after installation, these screw-in arrangements require assembly from numerous individual components and are held together by special fasteners which must pivot upon engagement and disengagement with the battery, and are therefore complex and expensive. Furthermore, the positioning of the various actuating arms above the vent caps is incompatible with a unitary construction and therefore precludes the use of this type of mechanism in a simplified filler cap environment.
While the use of individual filler units has been widely accepted in industry, they have not been popular in applications including electrically propelled golf carts. Unitary or ganged adaptations, as exemplified by a variety of vent cap arrangements, have proved elusive for implementation into filling system devices. The cost of installation and operation of available automatic battery filling technology has been too great to overcome the inconvenience of replenishing the electrolyte of the batteries manually.
A solution proposed in International application PCT/US97/04159 involves the incorporation of the entire filler mechanism into the structure of the lid of a battery, thereby eliminating a significant portion of the installation costs. This arrangement does, however, require filler maintenance as well as battery maintenance procedures to address the filler and the battery as a single indivisible unit, thereby incurring maintenance costs equating at all times to the combined maintenance of the filler plus the battery.
Implementation of a viable single point battery filling system for golf-carts has not been held back for a lack of technological improvisation, but rather due a lack of cost effective and convenient technology which is appropriate to this application.
According to the first aspect of the invention there is provided a filling system adapted to replenish a plurality of containers with liquid to a predetermined level within each container, the filling system comprising a feed unit defining a primary liquid reservoir, a filler unit defining a secondary liquid reservoir, and liquid feed and drain means arranged to allow liquid to be fed from the primary liquid reservoir to the secondary liquid reservoir to replenish the containers and to allow surplus liquid not required in the replenishment operation to drain from the secondary liquid reservoir, the filler unit including a plurality of outlet ports arranged to discharge liquid into a corresponding plurality of access openings in the containers.
In a preferred form of the invention, an attachment mechanism is provided for releasably attaching the outlet ports in flowing communication with the access openings.
Conveniently, the liquid feed and drain means comprises a single feed/drain line communicating between the primary and secondary liquid reservoirs, to the extent that the flow of feed liquid is reversed to allow surplus liquid to flow back into the primary reservoir.
Alternatively, the liquid feed and drain means comprises a feed line communicating between the primary and secondary reservoirs and a separate drain line communicating between the secondary reservoir and a separate liquid receiver for receiving surplus liquid from the secondary liquid reservoir.
Advantageously, the secondary reservoir has sufficient capacity to replenish the containers in a single filling operation, and the primary reservoir has sufficient capacity to allow for multiple filling operations of the secondary reservoir.
Preferably, the liquid feed and drain means and the outlet ports are dimensioned to ensure that the containers are replenished prior to the surplus liquid being allowed to drain completely from the secondary reservoir via the liquid feed and drain means.
Conveniently, the filler unit includes level control means for controlling the predetermined level to which each container is filled, and the feed unit includes feed and drain control means for feeding sufficient liquid into the secondary reservoir and for draining surplus liquid from the secondary reservoir.
In one form of the invention, the primary liquid reservoir includes a deformable bladder, and the feed and drain control means includes a pressure plate for operating the bladder, and biasing means for applying a predetermined bias to the pressure plate.
The biasing means may include a counterweight, and retaining means for selectively enabling the counterweight to act on the pressure plate during a downstroke of the pressure plate.
The retaining means may comprise a dished end of the pressure plate for receiving the counterweight, and a retaining bracket adjacent the dished end for temporarily retaining the counterweight on the dished end for facilitating a downstroke of the pressure plate.
In an alternative form of the invention, the feed unit includes an overhead tank arranged to gravity feed liquid into the secondary liquid reservoir via at least one first control valve, with the liquid similarly being drained from the secondary reservoir via at least one second control valve.
In a preferred alternative form of the invention, the primary liquid reservoir includes a feed tank and the feed and drain control means includes a motorized pump for discharging liquid from the feed tank into the secondary reservoir and for receiving surplus liquid from the secondary reservoir, and a control circuit for controlling the operation of the motorized pump.
Advantageously, the control circuit comprises sensing means for sensing when the tank is empty, based on current drawn by the pump motor, and switching means responsive to the sensing means for turning off the motor when the tank is empty.
The filling system is typically a battery watering system, in which the containers are an array of battery cells, and the access openings are conventional flanged cell replenishment apertures arranged to receive cell vent plugs in a screw fit.
The invention extends to an attachment mechanism for releasably attaching an overhead filler unit having a plurality of outlet ports to a plurality of liquid containers having a corresponding plurality of access openings into which the outlet ports are arranged to discharge liquid, the attachment mechanism comprising at least first and second inserts formed with first screw-type fittings and arranged to engage with complemental first screw-type fittings defined within the access openings, a pair of opposed outrigger arms extending from each insert, a pair of actuator arms joined to the ends of the outrigger arms by integrally formed hinges in a parallelogram configuration, and actuator means coupled to the first insert, whereby rotation of the first insert via the actuator means causes simultaneous rotation of the second insert for simultaneously rotating the first screw-type fittings of the first and second inserts into engagement with the complemental first screw-type fittings.
Preferably, the attachment mechanism includes a third insert formed with a first screw-type fitting for locating in a third access opening formed with a complemental first screw-type fitting, the first, second and third inserts being arranged in a linear array with a pair of opposed outrigger arms extending from the third insert and a pair of actuator arms joining the ends of the outrigger arms to the ends of the outrigger arms of the first insert via integrally formed hinges in a parallelogram configuration whereby rotation of the first insert is arranged to cause simultaneous and substantially identical rotation of the second and third inserts.
Conveniently, each of the outlet ports of the overhead filler unit comprises a restricted outlet orifice and a downpipe arranged to extend into an access opening of the liquid container, each of the downpipes being formed with a second screw-type fitting and the inserts being formed with second complemental screw-type fittings which are simultaneously engageable with the second screw-type fittings on rotation of the inserts.
Typically, each of the first screw-type fittings comprise pairs of outwardly extending bayonet lugs arranged to locate behind complemental bayonet ears defined within the access openings in the containers in a bayonet fit.
Advantageously, each of the second screw-type fittings comprise pairs of opposed bayonet lugs extending outwardly from the downpipes and the complemental second screw-type fittings comprise bayonet recesses defined in each of the inserts and arranged to be simultaneously brought into engaging alignment with the bayonet lugs.
The overhead filler unit is typically a battery watering unit, in which the liquid containers are an array of battery cells, and the access openings are conventional flanged cell replenishment apertures arranged to receive cell vent plugs in a screw fit.
By the term xe2x80x9cscrew-type fittingxe2x80x9d is meant any screw or bayonet fitting which employs a rotary or twisting motion.